Clostridioides difficile from Brazilian hospitals: characterization of virulence genes by whole genome sequencing.

Clostridioides difficile (CD) is the most frequent cause of healthcare related diarrhea and its severity has increased in the last decade by the spread of hypervirulent strains. Most important CD virulence factor is toxin production; however, not only toxins are responsible for Clostridioides virulence. We sequenced 38 strains and analyzed the presence and integrity of 24 virulence (including toxin) genes. We identified 28 toxigenic strains, six also presented the cdt genes. Only six strains didn't present all others genes searched. All absent genes were adhesion related. Understand others CD virulence factors can lead to a best understanding on this matter.

Alternative drugs against multiresistant Gram-negative bacteria.

OBJECTIVES: Enterobacterales and other non-fermenting Gram-negative bacteria have become a threat worldwide owing to the frequency of multidrug resistance in these pathogens. On the other hand, efficacious therapeutic options are quickly diminishing. The aims of this study were to describe the susceptibility of 50 multiresistant Gram-negative bacteria, mostly pan-resistant, against old and less-used antimicrobial drugs and to investigate the presence of antimicrobial resistance genes. METHODS: A total of 50 genetically distinct isolates were included in this study, including 14 Acinetobacter baumannii (belonging to ST79, ST317, ST835 and ST836), 1 Pseudomonas aeruginosa (ST245), 8 Serratia marcescens and 27 Klebsiella pneumoniae (belonging to ST11, ST340, ST258, ST16, ST23, ST25, ST101, ST234, ST437 and ST442). The isolates were submitted to antimicrobial susceptibility testing and whole-genome sequencing to evaluate lineages and resistance genes. RESULTS: Our results showed that some strains harboured carbapenemase genes, e.g. blaKPC-2 (28/50; 56%) and blaOXA-23 (11/50; 22%), and other resistance genes encoding aminoglycoside-modifying enzymes (49/50; 98%). Susceptibility rates to tigecycline (96%) in all species (except P. aeruginosa), to minocycline (100%) and doxycycline (93%) in A. baumannii, to ceftazidime/avibactam in S. marcescens (100%) and K. pneumoniae (96%), and to fosfomycin in S. marcescens (88%) were high. Chloramphenicol and quinolones (6% susceptibility each) did not perform well, making their use in an empirical scenario unlikely. CONCLUSIONS: This study involving genetically distinct bacteria showed promising results for tigecycline for all Gram-negative bacteria (except P. aeruginosa), and there was good activity of minocycline against A. baumannii, ceftazidime/avibactam against Enterobacterales, and fosfomycin against S. marcescens.

Polymyxin-resistant Pseudomonas aeruginosa assigned as ST245: First report in an intensive care unit in São Paulo, Brazil.

OBJECTIVES: Pseudomonas aeruginosa is a Gram-negative bacterium that causes severe infections, especially in hospitalised and immunocompromised patients. Polymyxins are the last therapeutic option to treat infections caused by this micro-organism. Here we describe a polymyxin-resistant P. aeruginosa assigned as sequence type (ST) 245 for the first time in Brazil. METHODS: Antimicrobial susceptibility testing of the isolate was performed. In addition, whole-genome sequencing was performed and its virulence and resistance genes were analysed. RESULTS: The P. aeruginosa ST245 isolate was identified for the first time in Brazil in a patient with ventilator-associated pneumonia hospitalised at Hospital das Clínicas, São Paulo. Analysis of the genome showed the presence of several resistance and virulence genes. Mutations in ß-lactam resistance genes were found in ß-lactamases, outer membrane proteins, efflux pump and penicillin-binding proteins. Polymorphisms related to pathways leading to polymyxin resistance are also present, such as lipid A or keto-deoxyoctulosonate modification with aminoarabinose as well as activation of lipopolysaccharide (LPS). CONCLUSION: Such findings may represent an alert for the spread of an unusual profile in the country.